An object of the present invention is to provide means capable of efficiently incorporating a substance useful for intestinal immunity induction such as lactic acid bacteria into the intestinal tract. According to the present invention, a substance uptake promoter in the intestine containing a surface protein (S-layer protein) containing a peptide motif common to Lactobacillus lactic acid bacteria, a complex of the uptake promoter and a substance to be intestinal uptake, There is provided a screening method for lactic acid bacteria having a high ability to enter the intestinal tract, which comprises measuring a food / beverage product or a pharmaceutical containing the complex and an expression level of S-layer protein in the surface layer of the test lactic acid bacteria.本発明は、乳酸菌などの腸管免疫誘導に有用な物質を効率的に腸管内に取り込むことのできる手段を提供することを課題とする。 本発明によれば、ラクトバチルス属乳酸菌に共通するペプチドモチーフを含む表層蛋白質(S-layer protein）を含む、腸管における物質取り込み促進剤、該取り込み促進剤と腸管取り込み対象物質との複合体、該複合体を含む飲食品または医薬品、ならびに被検乳酸菌の菌体表層におけるS-layer proteinの発現量を測定することを含む、腸管内移行能が高い乳酸菌のスクリーニング方法が提供される。
